Canada's cannabis legalization and adult crime patterns, 2015-2021: A time series study

Background and aim: A central goal of the Cannabis Act (October 17, 2018) - Canada's national cannabis legalization framework - aimed to reduce cannabis-related criminalization and consequent impact on the Canadian criminal justice system. We assessed whether Canada's cannabis legalization was associated with changes in adult police-reported cannabis-related, property, or violent criminal incidents. Design: Seasonal Autoregressive Integrated Moving Average (SARIMA) time series models evaluated relations between legalization and adult cannabis-related, property, and violent crimes, using criminal incident data from the Canadian Uniform Crime Reporting Survey (UCR-2; January 1, 2015-December 31, 2021). Primary sample: National police-reported adult cannabis-related offenses (n = 247,249), property crimes (n = 2,299,777), and violent crimes (n = 1,903,762). Findings: Implementation of the Cannabis Act was associated with decreases in adult police-reported cannabisrelated offenses: females, 13.2 daily incidents (95% CI, 16.4; 10.1; p < 0.001) - a reduction of 73.9% [standard error (se), 30.6%]; males, 69.4 daily offenses (95% CI, 81.5; 57.2; p < 0.001) - a drop of 83.2% (se, 21.2%). Legalization was not associated with significant changes in the adult property-crime or violent-crime series. Conclusions: Our findings suggest that Canada's cannabis legalization was successful in reducing cannabis-related criminalization among adults. There was also a lack of evidence for spillover effects of cannabis legalization on adult property or violent crimes.